The present invention relates to an impeller for a mixing apparatus; particularly for a mixture wherein at least one of the ingredients is in powder or particulate form.
The present inventor has recognized the need to be able to mix powder and other ingredients, which may be liquids, pastes or gels, and minimize the introduction of powder particles into the surrounding air. For example, in a beauty salon, powdered bleach is mixed with other hair coloring materials, the powdered bleach particles representing a health hazard to persons who would inhale them.
Typical mixing impellers employ blades, such as those described in Wheetman et al., U.S. Pat. No. 5,501,523 and Hill et al., U.S. Pat. No. 4,979,986, or teeth, such as described in Funk, U.S. Pat. No. 5,292,193. Splatter shields are also provided in the prior art, such as those described in Hawke, U.S. Pat. No. 3,913,896, Schiffner et al., U.S. Pat. No 4,549,811 and Sadek-Patt, U.S. Pat. No. 6,123,449. However, the present inventor is not aware of a mixing impeller or splatter shield optimally suited to minimize the contamination of surrounding air by substantially dry particulate matter as a result of the agitation involved in mixing. Blades and teeth roughly agitate and scatter particles such as dry powder in addition to mixing the particles, and prior art splatter shields such as that of the ""896 Patent provide openings through which the scattered particles can escape into the air both upwardly and radially outwardly
Accordingly, there is a need for an impeller and shield for a mixing apparatus that provides for minimizing the introduction of particulate matter into the air proximate a mixing operation at low cost.
The impeller and shield for a mixing apparatus of the present invention solves the aforementioned problems and meets the aforementioned needs by providing an impeller member having an upper face and a lower face that is at a lower elevation than the upper face, and one or more apertures extending through both faces. Each of the apertures has an upper periphery and a lower periphery that is at a lower elevation than the upper periphery. The apertures are formed such that the upper periphery is defined by an edge of the lower face and the lower periphery is defined by an edge of the upper face. The impeller member may be formed of a substantially planar plastic disc, wherein the apertures may be formed by cutting slits through the disc and deforming the plastic at the slits to xe2x80x9copen upxe2x80x9d the slits sufficiently to pass particles to be mixed. The impeller member is attached or attachable to a motor driven shaft.
Preferably, a separate shield member is also provided having upper and lower opposite surfaces and an aperture therethrough. The aperture of the shield member has a width dimension that is larger than the diameter of the shaft. A dust flap member is removably disposed over the slot, leaving, however, space for the shaft to penetrate through the slot, to hinder or prevent the slot from conducting particulate matter upwardly from the container to the surrounding air. The dust flap member preferably includes a plug portion adapted to extend into and block the slot, to hinder or prevent the slot from conducting particulate matter radially outwardly from the container to the surrounding air.
Therefore, it is a principal object of the present invention to provide a novel and improved impeller and shield for a mixing apparatus.
It is another object of the present invention to provide an impeller and shield for a mixing apparatus that provides for minimizing the introduction of particulate matter into the air surrounding a mixing operation.
It is yet another object of the present invention to provide such an impeller and shield that provides for economy of purchase and use.
The foregoing and other objects, features and advantages of the present invention will be more readily understood upon consideration of the following detailed description of the invention, taken in conjunction with the following drawings.